Place pork, onions, garlic,
tomatoes, cumin, mustard seeds, cinnamon, turmeric, chili paste
(sambal oelek), vinegar, sugar, yoghurt, lime juice and black pepper
to taste in a glass or ceramic bowl and mix to combine.
Cover and marinate in the
refrigerator for at least 3 hours.
Transfer pork mixture to a large
saucepan, stir in stock and bring to simmering.
Cover and simmer, stirring
occasionally, for 1 hour or until pork is tender.